Protractor.



No. 793,602. 4 PATBNTED JUNE 27, 1905. J. MURDUCK & V. L. LENARD.PROTRACTOR APPLICATION FILED APB.. 9,1904.

- N, l, .s

JOHN MURDOCK,

Patented June 2'7, 1905.

PATENT OEEICE.

OF HARTFORD, AND VICTOR L. LENARD, OF

POQUONOCK, CONNECTICUT.

PROTRACTOR.

SPECIFCATION forming part of Letters Patent No. 793,602, dated June 27,1905.

Application filed April 9, 1904. Serial No. 202,476.

To f/JZ Huh/om. it 77mg/ concern:

` Be it known that we, JOHN MURDooK,a resident of Hartford, and VICTORL. LENARD, a resident of Poquonoclr, in the county of Hartford and Stateof Connecticut, citizens of the United States, have invented a certainnew and useful Improvement in Protractors, of which the following is aspecification.

The invention relates to protractors or measuring devices for laying offpredetermined angles from a given point.

The object of the invention is to provide a protractor which will havegreat strength and will endure unusually hard usage, at the same timegiving readings of cxtreme accuracy.

A further object is to provide a protractor in which the protractor-armmay be readily swung to any desired position or may be set with thenicest degree of adjustment, reading either to degrees or to degrees andfractions thcreofas, for instance, minutes.

A still further object is to provide a protractor having a plurality ofrings mounted in a base and rotatable irrespective of each other or inconjunction with each other.

A still further object is to provide a base with a degree dial or ringand a minute dial or ring, the two arranged in conjunction with lockingdevices by which the two rings may be locked together or one of them maybe locked to the frame.

Finally, it is desired to produce a protractor in which thedegree-readings may be secured on one scale while the minute orfractional readings are secured on an entirely separate and distinctscale, securing what is practically a micrometer adjustment for thedegree-readings through the use of the minute-reading scale.

Referring to the drawings, Figure l is a view in elevation with partsbroken away to show construction. Fig. 2 is a cross-sectional viewthrough the device on the line 2 2 of Fig. 1. Fig. 3 is a detail Viewshowing the degreering and scale. Fig. 4: is a central verticalsectional View through the device on the line 4 4L of Fig. 1.

ln the accompanying drawings the letter a denotes the base having aring-like opening` within which is mounted a degree-plate Z. This plateis mortised into the frame and has on one side a scale Z2,divid ed intodegrees. The

. degree-plate has a hub c, extending through one face of the base, anda hub (Z, about which lits a second ring e. This ring at one sideterminates in a rack f or segment of a worm-wheel. It meshes with a wormg, mounted in an eX- tension c of the frame c. The ring e is cut away,as at e, and a binding-screw Z1., having a shoulder Zt', passes throughthe opening e and engages the edge of the degree-plate Z) for thepurpose of securing it positively to the frame in any desired positionof adjustment. A set-screw z' is also borne in the degree-plate b andhas its edge projecting over the hub (Z and arranged to engage and lockthe plate e to the degreeplate The extension c has at or near its upperend a Sleeve 7n', threaded on its interior and engaged by a fine threadg on the spindle which bears the worm g.y This spindle may. be formedintegral with or properly secured to a barrel-like thumb-piece Z, whichat its lower edge contains a clearly-marked scale Z and has its shelloverlying the sleeve Zr. This piece Z, together with the spindle, formmerely a micrometer adjustment for rotating either the plate c or thedegree-plate Z when the plates e and Z) are clamped together by theadjustingscrew c'. They further provide a means for reading fractions ofa degree.

It is to be noted that the worm g is of comparatively coarse pitch,while the threading at g is very line, and thus the travel of thespindle duc to the turning of the member Z will cause a comparativelyslight reciprocating movement of the spindle while it is turned, and adifferential movement is given to the plate e.

The protractor-blade m is secured to the degree-ring in any desiredmanner, as by being inserted in the saw-cut a, where it is held inproper adjustment by a set-screw o.

The operation of the device is as follows: The set-screws Zt and Z areloosened and the degree-plate is swung to any desired positionapproximately to zero. Thereupon the two plates Z) and a are clampedtogether by the setscrew c'. used for setting the degree-scale on theabsolute zero with the finest precision. When one is set at zero, thedegree-plate I) is tixed with reference. tothe support a by tighten ingthe setscrew la. The set-screw z' is now loosened, and themicrometer-handle l is turned until its scale reads Zero. By now turningthe set-screw z' and clamping the plates b and e together and at thesame time loosening the set-screw /t the micrometer-barrel may be turnedthrough the desired number of markings ofl its scale to give therequired minute-reading. It will thus be seen that the degree readingsare always taken from the degree-plate b, while the minute-readings aresecured on the scale of the micrometer-barrel l, and it is to be notedthat the micrometer-barrel has a double function. First of all, it maybe used for securing an accurate setting of the degreeplate, andsubsequently it may be used with great facility for securing readingsintermediate the degree-marks, thus giving the fractional readings forminutes.

Obviously various changes might he made in the details of constructionwithout departing from the intent or purpose of' the invention, andVarious connections might be used in lieu of the worm and thread betweenthe spindle ofthe micrometer-barrel and the worm-plate e.

It will be observed that the worm-plate e forms an adjusting means forthe deg ree-plate when clamped to it and also forms a connection fortranslating the movements of theV minute-reading spindle to thedegree-plate with thegreatest amount of' accuracy.

What we claim as our invention, and desire to secure by Letters Patent,is-

1. A protractor including a base, a degreering mounted to rotatetherein, a degree-scale on the degree-ring a spindle operativelyarranged with reference to the degree-plate and having another scaleappurtenant thereto but y independentof the degree-scale, andconnections intermediate the spindle and degree-plate whereby certainreadings may be secured upon the degree-plate and fractional readingssecured upon the scale of' the spindle.

2. In combination in a device of the class specified, a base or support,a degree-ring rotarily mounted therein and provided with a degree-scale,a protractor-blade secured thereto, an adjusting-ring operativelyarranged with reference to said degree-plate, a spindle, and connectionsintermediate the spindle and adj usting-ring for transmitting movementsof the former to the latter, and a scale appurtenant to the spindle forreading fractions of the scale of the degree-plate.

3. In combination in a device of the class rI he micrometer adjustmentis now specified, a base or support, a plurality of rings rotaril ymounted therein, means for clamping said rings together and means forlocking one or both of Isaid rings to the support, a spindleappurtenantto the support and connected with one of said rings to rotateit, and a scale appurtenant to the spindle whereby the angular movementsof the plate or plates eected by the spindle may be read.

4. In combination in a device of the class specified, a base or support,a degree-ring mounted therein, an adjusting-ring operatively arrangedwith reference to the degreering, means for clamping said ringstogether, a spindle appurtenant to the support and connected with saidadjusting-ring whereby movements of the -spindle are transmitted to saidring, and a scale appurtenant to the spindle indicating the movements ofthe adjustingring.

5. In a device of the class specified, a base or support, a degree-ringmounted to rotate therein, an adjusting-ring concentrically arrangedwith reference to the degree-ring, a spindle appurtenant to the-supportand provided with a threaded portion, an interengaging thread arrangedupon the adjusting-ring, and clamping devices for securing said ringstogether for simultaneous movement or locking the degree-ring withreference to the support, irrespective of the adjusting-ring.

6. ln a device of the class specified, a support, a degree-ring rotarilymounted therein and provided with a scale of certain units, amicrometer-spindle -appurtenant to said degree-plate and frame, andprovided with a scale for reading fractions of' the units of the scaleof the degree-ring, and connections intermediate said spindle anddegree-ring whereby the scale of' the degree-ring or the scale of themicrometer-spindle may be set to the Zeropoint independently.

7. In combination in a device of the class specified, a support arrangedto receive a degree-ring, a boss appurtenant to said support providedwith an opening, a screw-threaded sleeve arranged within the opening andprojecting therefrom, a spindle having a screwthread meshing with thethread of said sleeve and provided with a barrel overlying the sleeve, asecond thread arranged upon the sleeve, and connections intermediatesaid thread and the degree-plate for moving the latter upon apredetermined movement of' the spindle.

JOHN MURDOCK. VICTOR L. LEN ARD. l/Vitncsscs:

WM. H. BARKER, E. R. BARKER.

IOO

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